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-rw-r--r--arch/arm64/kernel/fpsimd.c908
1 files changed, 881 insertions, 27 deletions
diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 5d547deb6996..143b3e72c25e 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -17,19 +17,34 @@
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
+#include <linux/bitmap.h>
#include <linux/bottom_half.h>
+#include <linux/bug.h>
+#include <linux/cache.h>
+#include <linux/compat.h>
#include <linux/cpu.h>
#include <linux/cpu_pm.h>
#include <linux/kernel.h>
+#include <linux/linkage.h>
+#include <linux/irqflags.h>
#include <linux/init.h>
#include <linux/percpu.h>
+#include <linux/prctl.h>
#include <linux/preempt.h>
+#include <linux/prctl.h>
+#include <linux/ptrace.h>
#include <linux/sched/signal.h>
+#include <linux/sched/task_stack.h>
#include <linux/signal.h>
+#include <linux/slab.h>
+#include <linux/sysctl.h>
#include <asm/fpsimd.h>
#include <asm/cputype.h>
#include <asm/simd.h>
+#include <asm/sigcontext.h>
+#include <asm/sysreg.h>
+#include <asm/traps.h>
#define FPEXC_IOF (1 << 0)
#define FPEXC_DZF (1 << 1)
@@ -39,6 +54,8 @@
#define FPEXC_IDF (1 << 7)
/*
+ * (Note: in this discussion, statements about FPSIMD apply equally to SVE.)
+ *
* In order to reduce the number of times the FPSIMD state is needlessly saved
* and restored, we need to keep track of two things:
* (a) for each task, we need to remember which CPU was the last one to have
@@ -99,10 +116,741 @@
*/
static DEFINE_PER_CPU(struct fpsimd_state *, fpsimd_last_state);
+/* Default VL for tasks that don't set it explicitly: */
+static int sve_default_vl = -1;
+
+#ifdef CONFIG_ARM64_SVE
+
+/* Maximum supported vector length across all CPUs (initially poisoned) */
+int __ro_after_init sve_max_vl = -1;
+/* Set of available vector lengths, as vq_to_bit(vq): */
+static __ro_after_init DECLARE_BITMAP(sve_vq_map, SVE_VQ_MAX);
+static void __percpu *efi_sve_state;
+
+#else /* ! CONFIG_ARM64_SVE */
+
+/* Dummy declaration for code that will be optimised out: */
+extern __ro_after_init DECLARE_BITMAP(sve_vq_map, SVE_VQ_MAX);
+extern void __percpu *efi_sve_state;
+
+#endif /* ! CONFIG_ARM64_SVE */
+
+/*
+ * Call __sve_free() directly only if you know task can't be scheduled
+ * or preempted.
+ */
+static void __sve_free(struct task_struct *task)
+{
+ kfree(task->thread.sve_state);
+ task->thread.sve_state = NULL;
+}
+
+static void sve_free(struct task_struct *task)
+{
+ WARN_ON(test_tsk_thread_flag(task, TIF_SVE));
+
+ __sve_free(task);
+}
+
+
+/* Offset of FFR in the SVE register dump */
+static size_t sve_ffr_offset(int vl)
+{
+ return SVE_SIG_FFR_OFFSET(sve_vq_from_vl(vl)) - SVE_SIG_REGS_OFFSET;
+}
+
+static void *sve_pffr(struct task_struct *task)
+{
+ return (char *)task->thread.sve_state +
+ sve_ffr_offset(task->thread.sve_vl);
+}
+
+static void change_cpacr(u64 val, u64 mask)
+{
+ u64 cpacr = read_sysreg(CPACR_EL1);
+ u64 new = (cpacr & ~mask) | val;
+
+ if (new != cpacr)
+ write_sysreg(new, CPACR_EL1);
+}
+
+static void sve_user_disable(void)
+{
+ change_cpacr(0, CPACR_EL1_ZEN_EL0EN);
+}
+
+static void sve_user_enable(void)
+{
+ change_cpacr(CPACR_EL1_ZEN_EL0EN, CPACR_EL1_ZEN_EL0EN);
+}
+
+/*
+ * TIF_SVE controls whether a task can use SVE without trapping while
+ * in userspace, and also the way a task's FPSIMD/SVE state is stored
+ * in thread_struct.
+ *
+ * The kernel uses this flag to track whether a user task is actively
+ * using SVE, and therefore whether full SVE register state needs to
+ * be tracked. If not, the cheaper FPSIMD context handling code can
+ * be used instead of the more costly SVE equivalents.
+ *
+ * * TIF_SVE set:
+ *
+ * The task can execute SVE instructions while in userspace without
+ * trapping to the kernel.
+ *
+ * When stored, Z0-Z31 (incorporating Vn in bits[127:0] or the
+ * corresponding Zn), P0-P15 and FFR are encoded in in
+ * task->thread.sve_state, formatted appropriately for vector
+ * length task->thread.sve_vl.
+ *
+ * task->thread.sve_state must point to a valid buffer at least
+ * sve_state_size(task) bytes in size.
+ *
+ * During any syscall, the kernel may optionally clear TIF_SVE and
+ * discard the vector state except for the FPSIMD subset.
+ *
+ * * TIF_SVE clear:
+ *
+ * An attempt by the user task to execute an SVE instruction causes
+ * do_sve_acc() to be called, which does some preparation and then
+ * sets TIF_SVE.
+ *
+ * When stored, FPSIMD registers V0-V31 are encoded in
+ * task->fpsimd_state; bits [max : 128] for each of Z0-Z31 are
+ * logically zero but not stored anywhere; P0-P15 and FFR are not
+ * stored and have unspecified values from userspace's point of
+ * view. For hygiene purposes, the kernel zeroes them on next use,
+ * but userspace is discouraged from relying on this.
+ *
+ * task->thread.sve_state does not need to be non-NULL, valid or any
+ * particular size: it must not be dereferenced.
+ *
+ * * FPSR and FPCR are always stored in task->fpsimd_state irrespctive of
+ * whether TIF_SVE is clear or set, since these are not vector length
+ * dependent.
+ */
+
+/*
+ * Update current's FPSIMD/SVE registers from thread_struct.
+ *
+ * This function should be called only when the FPSIMD/SVE state in
+ * thread_struct is known to be up to date, when preparing to enter
+ * userspace.
+ *
+ * Softirqs (and preemption) must be disabled.
+ */
+static void task_fpsimd_load(void)
+{
+ WARN_ON(!in_softirq() && !irqs_disabled());
+
+ if (system_supports_sve() && test_thread_flag(TIF_SVE))
+ sve_load_state(sve_pffr(current),
+ &current->thread.fpsimd_state.fpsr,
+ sve_vq_from_vl(current->thread.sve_vl) - 1);
+ else
+ fpsimd_load_state(&current->thread.fpsimd_state);
+
+ if (system_supports_sve()) {
+ /* Toggle SVE trapping for userspace if needed */
+ if (test_thread_flag(TIF_SVE))
+ sve_user_enable();
+ else
+ sve_user_disable();
+
+ /* Serialised by exception return to user */
+ }
+}
+
+/*
+ * Ensure current's FPSIMD/SVE storage in thread_struct is up to date
+ * with respect to the CPU registers.
+ *
+ * Softirqs (and preemption) must be disabled.
+ */
+static void task_fpsimd_save(void)
+{
+ WARN_ON(!in_softirq() && !irqs_disabled());
+
+ if (!test_thread_flag(TIF_FOREIGN_FPSTATE)) {
+ if (system_supports_sve() && test_thread_flag(TIF_SVE)) {
+ if (WARN_ON(sve_get_vl() != current->thread.sve_vl)) {
+ /*
+ * Can't save the user regs, so current would
+ * re-enter user with corrupt state.
+ * There's no way to recover, so kill it:
+ */
+ force_signal_inject(
+ SIGKILL, 0, current_pt_regs(), 0);
+ return;
+ }
+
+ sve_save_state(sve_pffr(current),
+ &current->thread.fpsimd_state.fpsr);
+ } else
+ fpsimd_save_state(&current->thread.fpsimd_state);
+ }
+}
+
+/*
+ * Helpers to translate bit indices in sve_vq_map to VQ values (and
+ * vice versa). This allows find_next_bit() to be used to find the
+ * _maximum_ VQ not exceeding a certain value.
+ */
+
+static unsigned int vq_to_bit(unsigned int vq)
+{
+ return SVE_VQ_MAX - vq;
+}
+
+static unsigned int bit_to_vq(unsigned int bit)
+{
+ if (WARN_ON(bit >= SVE_VQ_MAX))
+ bit = SVE_VQ_MAX - 1;
+
+ return SVE_VQ_MAX - bit;
+}
+
+/*
+ * All vector length selection from userspace comes through here.
+ * We're on a slow path, so some sanity-checks are included.
+ * If things go wrong there's a bug somewhere, but try to fall back to a
+ * safe choice.
+ */
+static unsigned int find_supported_vector_length(unsigned int vl)
+{
+ int bit;
+ int max_vl = sve_max_vl;
+
+ if (WARN_ON(!sve_vl_valid(vl)))
+ vl = SVE_VL_MIN;
+
+ if (WARN_ON(!sve_vl_valid(max_vl)))
+ max_vl = SVE_VL_MIN;
+
+ if (vl > max_vl)
+ vl = max_vl;
+
+ bit = find_next_bit(sve_vq_map, SVE_VQ_MAX,
+ vq_to_bit(sve_vq_from_vl(vl)));
+ return sve_vl_from_vq(bit_to_vq(bit));
+}
+
+#ifdef CONFIG_SYSCTL
+
+static int sve_proc_do_default_vl(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp,
+ loff_t *ppos)
+{
+ int ret;
+ int vl = sve_default_vl;
+ struct ctl_table tmp_table = {
+ .data = &vl,
+ .maxlen = sizeof(vl),
+ };
+
+ ret = proc_dointvec(&tmp_table, write, buffer, lenp, ppos);
+ if (ret || !write)
+ return ret;
+
+ /* Writing -1 has the special meaning "set to max": */
+ if (vl == -1) {
+ /* Fail safe if sve_max_vl wasn't initialised */
+ if (WARN_ON(!sve_vl_valid(sve_max_vl)))
+ vl = SVE_VL_MIN;
+ else
+ vl = sve_max_vl;
+
+ goto chosen;
+ }
+
+ if (!sve_vl_valid(vl))
+ return -EINVAL;
+
+ vl = find_supported_vector_length(vl);
+chosen:
+ sve_default_vl = vl;
+ return 0;
+}
+
+static struct ctl_table sve_default_vl_table[] = {
+ {
+ .procname = "sve_default_vector_length",
+ .mode = 0644,
+ .proc_handler = sve_proc_do_default_vl,
+ },
+ { }
+};
+
+static int __init sve_sysctl_init(void)
+{
+ if (system_supports_sve())
+ if (!register_sysctl("abi", sve_default_vl_table))
+ return -EINVAL;
+
+ return 0;
+}
+
+#else /* ! CONFIG_SYSCTL */
+static int __init sve_sysctl_init(void) { return 0; }
+#endif /* ! CONFIG_SYSCTL */
+
+#define ZREG(sve_state, vq, n) ((char *)(sve_state) + \
+ (SVE_SIG_ZREG_OFFSET(vq, n) - SVE_SIG_REGS_OFFSET))
+
+/*
+ * Transfer the FPSIMD state in task->thread.fpsimd_state to
+ * task->thread.sve_state.
+ *
+ * Task can be a non-runnable task, or current. In the latter case,
+ * softirqs (and preemption) must be disabled.
+ * task->thread.sve_state must point to at least sve_state_size(task)
+ * bytes of allocated kernel memory.
+ * task->thread.fpsimd_state must be up to date before calling this function.
+ */
+static void fpsimd_to_sve(struct task_struct *task)
+{
+ unsigned int vq;
+ void *sst = task->thread.sve_state;
+ struct fpsimd_state const *fst = &task->thread.fpsimd_state;
+ unsigned int i;
+
+ if (!system_supports_sve())
+ return;
+
+ vq = sve_vq_from_vl(task->thread.sve_vl);
+ for (i = 0; i < 32; ++i)
+ memcpy(ZREG(sst, vq, i), &fst->vregs[i],
+ sizeof(fst->vregs[i]));
+}
+
+/*
+ * Transfer the SVE state in task->thread.sve_state to
+ * task->thread.fpsimd_state.
+ *
+ * Task can be a non-runnable task, or current. In the latter case,
+ * softirqs (and preemption) must be disabled.
+ * task->thread.sve_state must point to at least sve_state_size(task)
+ * bytes of allocated kernel memory.
+ * task->thread.sve_state must be up to date before calling this function.
+ */
+static void sve_to_fpsimd(struct task_struct *task)
+{
+ unsigned int vq;
+ void const *sst = task->thread.sve_state;
+ struct fpsimd_state *fst = &task->thread.fpsimd_state;
+ unsigned int i;
+
+ if (!system_supports_sve())
+ return;
+
+ vq = sve_vq_from_vl(task->thread.sve_vl);
+ for (i = 0; i < 32; ++i)
+ memcpy(&fst->vregs[i], ZREG(sst, vq, i),
+ sizeof(fst->vregs[i]));
+}
+
+#ifdef CONFIG_ARM64_SVE
+
+/*
+ * Return how many bytes of memory are required to store the full SVE
+ * state for task, given task's currently configured vector length.
+ */
+size_t sve_state_size(struct task_struct const *task)
+{
+ return SVE_SIG_REGS_SIZE(sve_vq_from_vl(task->thread.sve_vl));
+}
+
+/*
+ * Ensure that task->thread.sve_state is allocated and sufficiently large.
+ *
+ * This function should be used only in preparation for replacing
+ * task->thread.sve_state with new data. The memory is always zeroed
+ * here to prevent stale data from showing through: this is done in
+ * the interest of testability and predictability: except in the
+ * do_sve_acc() case, there is no ABI requirement to hide stale data
+ * written previously be task.
+ */
+void sve_alloc(struct task_struct *task)
+{
+ if (task->thread.sve_state) {
+ memset(task->thread.sve_state, 0, sve_state_size(current));
+ return;
+ }
+
+ /* This is a small allocation (maximum ~8KB) and Should Not Fail. */
+ task->thread.sve_state =
+ kzalloc(sve_state_size(task), GFP_KERNEL);
+
+ /*
+ * If future SVE revisions can have larger vectors though,
+ * this may cease to be true:
+ */
+ BUG_ON(!task->thread.sve_state);
+}
+
+
+/*
+ * Ensure that task->thread.sve_state is up to date with respect to
+ * the user task, irrespective of when SVE is in use or not.
+ *
+ * This should only be called by ptrace. task must be non-runnable.
+ * task->thread.sve_state must point to at least sve_state_size(task)
+ * bytes of allocated kernel memory.
+ */
+void fpsimd_sync_to_sve(struct task_struct *task)
+{
+ if (!test_tsk_thread_flag(task, TIF_SVE))
+ fpsimd_to_sve(task);
+}
+
+/*
+ * Ensure that task->thread.fpsimd_state is up to date with respect to
+ * the user task, irrespective of whether SVE is in use or not.
+ *
+ * This should only be called by ptrace. task must be non-runnable.
+ * task->thread.sve_state must point to at least sve_state_size(task)
+ * bytes of allocated kernel memory.
+ */
+void sve_sync_to_fpsimd(struct task_struct *task)
+{
+ if (test_tsk_thread_flag(task, TIF_SVE))
+ sve_to_fpsimd(task);
+}
+
+/*
+ * Ensure that task->thread.sve_state is up to date with respect to
+ * the task->thread.fpsimd_state.
+ *
+ * This should only be called by ptrace to merge new FPSIMD register
+ * values into a task for which SVE is currently active.
+ * task must be non-runnable.
+ * task->thread.sve_state must point to at least sve_state_size(task)
+ * bytes of allocated kernel memory.
+ * task->thread.fpsimd_state must already have been initialised with
+ * the new FPSIMD register values to be merged in.
+ */
+void sve_sync_from_fpsimd_zeropad(struct task_struct *task)
+{
+ unsigned int vq;
+ void *sst = task->thread.sve_state;
+ struct fpsimd_state const *fst = &task->thread.fpsimd_state;
+ unsigned int i;
+
+ if (!test_tsk_thread_flag(task, TIF_SVE))
+ return;
+
+ vq = sve_vq_from_vl(task->thread.sve_vl);
+
+ memset(sst, 0, SVE_SIG_REGS_SIZE(vq));
+
+ for (i = 0; i < 32; ++i)
+ memcpy(ZREG(sst, vq, i), &fst->vregs[i],
+ sizeof(fst->vregs[i]));
+}
+
+int sve_set_vector_length(struct task_struct *task,
+ unsigned long vl, unsigned long flags)
+{
+ if (flags & ~(unsigned long)(PR_SVE_VL_INHERIT |
+ PR_SVE_SET_VL_ONEXEC))
+ return -EINVAL;
+
+ if (!sve_vl_valid(vl))
+ return -EINVAL;
+
+ /*
+ * Clamp to the maximum vector length that VL-agnostic SVE code can
+ * work with. A flag may be assigned in the future to allow setting
+ * of larger vector lengths without confusing older software.
+ */
+ if (vl > SVE_VL_ARCH_MAX)
+ vl = SVE_VL_ARCH_MAX;
+
+ vl = find_supported_vector_length(vl);
+
+ if (flags & (PR_SVE_VL_INHERIT |
+ PR_SVE_SET_VL_ONEXEC))
+ task->thread.sve_vl_onexec = vl;
+ else
+ /* Reset VL to system default on next exec: */
+ task->thread.sve_vl_onexec = 0;
+
+ /* Only actually set the VL if not deferred: */
+ if (flags & PR_SVE_SET_VL_ONEXEC)
+ goto out;
+
+ if (vl == task->thread.sve_vl)
+ goto out;
+
+ /*
+ * To ensure the FPSIMD bits of the SVE vector registers are preserved,
+ * write any live register state back to task_struct, and convert to a
+ * non-SVE thread.
+ */
+ if (task == current) {
+ local_bh_disable();
+
+ task_fpsimd_save();
+ set_thread_flag(TIF_FOREIGN_FPSTATE);
+ }
+
+ fpsimd_flush_task_state(task);
+ if (test_and_clear_tsk_thread_flag(task, TIF_SVE))
+ sve_to_fpsimd(task);
+
+ if (task == current)
+ local_bh_enable();
+
+ /*
+ * Force reallocation of task SVE state to the correct size
+ * on next use:
+ */
+ sve_free(task);
+
+ task->thread.sve_vl = vl;
+
+out:
+ if (flags & PR_SVE_VL_INHERIT)
+ set_tsk_thread_flag(task, TIF_SVE_VL_INHERIT);
+ else
+ clear_tsk_thread_flag(task, TIF_SVE_VL_INHERIT);
+
+ return 0;
+}
+
+/*
+ * Encode the current vector length and flags for return.
+ * This is only required for prctl(): ptrace has separate fields
+ *
+ * flags are as for sve_set_vector_length().
+ */
+static int sve_prctl_status(unsigned long flags)
+{
+ int ret;
+
+ if (flags & PR_SVE_SET_VL_ONEXEC)
+ ret = current->thread.sve_vl_onexec;
+ else
+ ret = current->thread.sve_vl;
+
+ if (test_thread_flag(TIF_SVE_VL_INHERIT))
+ ret |= PR_SVE_VL_INHERIT;
+
+ return ret;
+}
+
+/* PR_SVE_SET_VL */
+int sve_set_current_vl(unsigned long arg)
+{
+ unsigned long vl, flags;
+ int ret;
+
+ vl = arg & PR_SVE_VL_LEN_MASK;
+ flags = arg & ~vl;
+
+ if (!system_supports_sve())
+ return -EINVAL;
+
+ ret = sve_set_vector_length(current, vl, flags);
+ if (ret)
+ return ret;
+
+ return sve_prctl_status(flags);
+}
+
+/* PR_SVE_GET_VL */
+int sve_get_current_vl(void)
+{
+ if (!system_supports_sve())
+ return -EINVAL;
+
+ return sve_prctl_status(0);
+}
+
+/*
+ * Bitmap for temporary storage of the per-CPU set of supported vector lengths
+ * during secondary boot.
+ */
+static DECLARE_BITMAP(sve_secondary_vq_map, SVE_VQ_MAX);
+
+static void sve_probe_vqs(DECLARE_BITMAP(map, SVE_VQ_MAX))
+{
+ unsigned int vq, vl;
+ unsigned long zcr;
+
+ bitmap_zero(map, SVE_VQ_MAX);
+
+ zcr = ZCR_ELx_LEN_MASK;
+ zcr = read_sysreg_s(SYS_ZCR_EL1) & ~zcr;
+
+ for (vq = SVE_VQ_MAX; vq >= SVE_VQ_MIN; --vq) {
+ write_sysreg_s(zcr | (vq - 1), SYS_ZCR_EL1); /* self-syncing */
+ vl = sve_get_vl();
+ vq = sve_vq_from_vl(vl); /* skip intervening lengths */
+ set_bit(vq_to_bit(vq), map);
+ }
+}
+
+void __init sve_init_vq_map(void)
+{
+ sve_probe_vqs(sve_vq_map);
+}
+
+/*
+ * If we haven't committed to the set of supported VQs yet, filter out
+ * those not supported by the current CPU.
+ */
+void sve_update_vq_map(void)
+{
+ sve_probe_vqs(sve_secondary_vq_map);
+ bitmap_and(sve_vq_map, sve_vq_map, sve_secondary_vq_map, SVE_VQ_MAX);
+}
+
+/* Check whether the current CPU supports all VQs in the committed set */
+int sve_verify_vq_map(void)
+{
+ int ret = 0;
+
+ sve_probe_vqs(sve_secondary_vq_map);
+ bitmap_andnot(sve_secondary_vq_map, sve_vq_map, sve_secondary_vq_map,
+ SVE_VQ_MAX);
+ if (!bitmap_empty(sve_secondary_vq_map, SVE_VQ_MAX)) {
+ pr_warn("SVE: cpu%d: Required vector length(s) missing\n",
+ smp_processor_id());
+ ret = -EINVAL;
+ }
+
+ return ret;
+}
+
+static void __init sve_efi_setup(void)
+{
+ if (!IS_ENABLED(CONFIG_EFI))
+ return;
+
+ /*
+ * alloc_percpu() warns and prints a backtrace if this goes wrong.
+ * This is evidence of a crippled system and we are returning void,
+ * so no attempt is made to handle this situation here.
+ */
+ if (!sve_vl_valid(sve_max_vl))
+ goto fail;
+
+ efi_sve_state = __alloc_percpu(
+ SVE_SIG_REGS_SIZE(sve_vq_from_vl(sve_max_vl)), SVE_VQ_BYTES);
+ if (!efi_sve_state)
+ goto fail;
+
+ return;
+
+fail:
+ panic("Cannot allocate percpu memory for EFI SVE save/restore");
+}
+
+/*
+ * Enable SVE for EL1.
+ * Intended for use by the cpufeatures code during CPU boot.
+ */
+int sve_kernel_enable(void *__always_unused p)
+{
+ write_sysreg(read_sysreg(CPACR_EL1) | CPACR_EL1_ZEN_EL1EN, CPACR_EL1);
+ isb();
+
+ return 0;
+}
+
+void __init sve_setup(void)
+{
+ u64 zcr;
+
+ if (!system_supports_sve())
+ return;
+
+ /*
+ * The SVE architecture mandates support for 128-bit vectors,
+ * so sve_vq_map must have at least SVE_VQ_MIN set.
+ * If something went wrong, at least try to patch it up:
+ */
+ if (WARN_ON(!test_bit(vq_to_bit(SVE_VQ_MIN), sve_vq_map)))
+ set_bit(vq_to_bit(SVE_VQ_MIN), sve_vq_map);
+
+ zcr = read_sanitised_ftr_reg(SYS_ZCR_EL1);
+ sve_max_vl = sve_vl_from_vq((zcr & ZCR_ELx_LEN_MASK) + 1);
+
+ /*
+ * Sanity-check that the max VL we determined through CPU features
+ * corresponds properly to sve_vq_map. If not, do our best:
+ */
+ if (WARN_ON(sve_max_vl != find_supported_vector_length(sve_max_vl)))
+ sve_max_vl = find_supported_vector_length(sve_max_vl);
+
+ /*
+ * For the default VL, pick the maximum supported value <= 64.
+ * VL == 64 is guaranteed not to grow the signal frame.
+ */
+ sve_default_vl = find_supported_vector_length(64);
+
+ pr_info("SVE: maximum available vector length %u bytes per vector\n",
+ sve_max_vl);
+ pr_info("SVE: default vector length %u bytes per vector\n",
+ sve_default_vl);
+
+ sve_efi_setup();
+}
+
+/*
+ * Called from the put_task_struct() path, which cannot get here
+ * unless dead_task is really dead and not schedulable.
+ */
+void fpsimd_release_task(struct task_struct *dead_task)
+{
+ __sve_free(dead_task);
+}
+
+#endif /* CONFIG_ARM64_SVE */
+
+/*
+ * Trapped SVE access
+ *
+ * Storage is allocated for the full SVE state, the current FPSIMD
+ * register contents are migrated across, and TIF_SVE is set so that
+ * the SVE access trap will be disabled the next time this task
+ * reaches ret_to_user.
+ *
+ * TIF_SVE should be clear on entry: otherwise, task_fpsimd_load()
+ * would have disabled the SVE access trap for userspace during
+ * ret_to_user, making an SVE access trap impossible in that case.
+ */
+asmlinkage void do_sve_acc(unsigned int esr, struct pt_regs *regs)
+{
+ /* Even if we chose not to use SVE, the hardware could still trap: */
+ if (unlikely(!system_supports_sve()) || WARN_ON(is_compat_task())) {
+ force_signal_inject(SIGILL, ILL_ILLOPC, regs, 0);
+ return;
+ }
+
+ sve_alloc(current);
+
+ local_bh_disable();
+
+ task_fpsimd_save();
+ fpsimd_to_sve(current);
+
+ /* Force ret_to_user to reload the registers: */
+ fpsimd_flush_task_state(current);
+ set_thread_flag(TIF_FOREIGN_FPSTATE);
+
+ if (test_and_set_thread_flag(TIF_SVE))
+ WARN_ON(1); /* SVE access shouldn't have trapped */
+
+ local_bh_enable();
+}
+
/*
* Trapped FP/ASIMD access.
*/
-void do_fpsimd_acc(unsigned int esr, struct pt_regs *regs)
+asmlinkage void do_fpsimd_acc(unsigned int esr, struct pt_regs *regs)
{
/* TODO: implement lazy context saving/restoring */
WARN_ON(1);
@@ -111,7 +859,7 @@ void do_fpsimd_acc(unsigned int esr, struct pt_regs *regs)
/*
* Raise a SIGFPE for the current process.
*/
-void do_fpsimd_exc(unsigned int esr, struct pt_regs *regs)
+asmlinkage void do_fpsimd_exc(unsigned int esr, struct pt_regs *regs)
{
siginfo_t info;
unsigned int si_code = 0;
@@ -144,8 +892,8 @@ void fpsimd_thread_switch(struct task_struct *next)
* the registers is in fact the most recent userland FPSIMD state of
* 'current'.
*/
- if (current->mm && !test_thread_flag(TIF_FOREIGN_FPSTATE))
- fpsimd_save_state(&current->thread.fpsimd_state);
+ if (current->mm)
+ task_fpsimd_save();
if (next->mm) {
/*
@@ -159,16 +907,16 @@ void fpsimd_thread_switch(struct task_struct *next)
if (__this_cpu_read(fpsimd_last_state) == st
&& st->cpu == smp_processor_id())
- clear_ti_thread_flag(task_thread_info(next),
- TIF_FOREIGN_FPSTATE);
+ clear_tsk_thread_flag(next, TIF_FOREIGN_FPSTATE);
else
- set_ti_thread_flag(task_thread_info(next),
- TIF_FOREIGN_FPSTATE);
+ set_tsk_thread_flag(next, TIF_FOREIGN_FPSTATE);
}
}
void fpsimd_flush_thread(void)
{
+ int vl, supported_vl;
+
if (!system_supports_fpsimd())
return;
@@ -176,6 +924,42 @@ void fpsimd_flush_thread(void)
memset(&current->thread.fpsimd_state, 0, sizeof(struct fpsimd_state));
fpsimd_flush_task_state(current);
+
+ if (system_supports_sve()) {
+ clear_thread_flag(TIF_SVE);
+ sve_free(current);
+
+ /*
+ * Reset the task vector length as required.
+ * This is where we ensure that all user tasks have a valid
+ * vector length configured: no kernel task can become a user
+ * task without an exec and hence a call to this function.
+ * By the time the first call to this function is made, all
+ * early hardware probing is complete, so sve_default_vl
+ * should be valid.
+ * If a bug causes this to go wrong, we make some noise and
+ * try to fudge thread.sve_vl to a safe value here.
+ */
+ vl = current->thread.sve_vl_onexec ?
+ current->thread.sve_vl_onexec : sve_default_vl;
+
+ if (WARN_ON(!sve_vl_valid(vl)))
+ vl = SVE_VL_MIN;
+
+ supported_vl = find_supported_vector_length(vl);
+ if (WARN_ON(supported_vl != vl))
+ vl = supported_vl;
+
+ current->thread.sve_vl = vl;
+
+ /*
+ * If the task is not set to inherit, ensure that the vector
+ * length will be reset by a subsequent exec:
+ */
+ if (!test_thread_flag(TIF_SVE_VL_INHERIT))
+ current->thread.sve_vl_onexec = 0;
+ }
+
set_thread_flag(TIF_FOREIGN_FPSTATE);
local_bh_enable();
@@ -191,14 +975,23 @@ void fpsimd_preserve_current_state(void)
return;
local_bh_disable();
-
- if (!test_thread_flag(TIF_FOREIGN_FPSTATE))
- fpsimd_save_state(&current->thread.fpsimd_state);
-
+ task_fpsimd_save();
local_bh_enable();
}
/*
+ * Like fpsimd_preserve_current_state(), but ensure that
+ * current->thread.fpsimd_state is updated so that it can be copied to
+ * the signal frame.
+ */
+void fpsimd_signal_preserve_current_state(void)
+{
+ fpsimd_preserve_current_state();
+ if (system_supports_sve() && test_thread_flag(TIF_SVE))
+ sve_to_fpsimd(current);
+}
+
+/*
* Load the userland FPSIMD state of 'current' from memory, but only if the
* FPSIMD state already held in the registers is /not/ the most recent FPSIMD
* state of 'current'
@@ -213,7 +1006,7 @@ void fpsimd_restore_current_state(void)
if (test_and_clear_thread_flag(TIF_FOREIGN_FPSTATE)) {
struct fpsimd_state *st = &current->thread.fpsimd_state;
- fpsimd_load_state(st);
+ task_fpsimd_load();
__this_cpu_write(fpsimd_last_state, st);
st->cpu = smp_processor_id();
}
@@ -233,7 +1026,12 @@ void fpsimd_update_current_state(struct fpsimd_state *state)
local_bh_disable();
- fpsimd_load_state(state);
+ if (system_supports_sve() && test_thread_flag(TIF_SVE)) {
+ current->thread.fpsimd_state = *state;
+ fpsimd_to_sve(current);
+ }
+ task_fpsimd_load();
+
if (test_and_clear_thread_flag(TIF_FOREIGN_FPSTATE)) {
struct fpsimd_state *st = &current->thread.fpsimd_state;
@@ -252,6 +1050,33 @@ void fpsimd_flush_task_state(struct task_struct *t)
t->thread.fpsimd_state.cpu = NR_CPUS;
}
+static inline void fpsimd_flush_cpu_state(void)
+{
+ __this_cpu_write(fpsimd_last_state, NULL);
+}
+
+/*
+ * Invalidate any task SVE state currently held in this CPU's regs.
+ *
+ * This is used to prevent the kernel from trying to reuse SVE register data
+ * that is detroyed by KVM guest enter/exit. This function should go away when
+ * KVM SVE support is implemented. Don't use it for anything else.
+ */
+#ifdef CONFIG_ARM64_SVE
+void sve_flush_cpu_state(void)
+{
+ struct fpsimd_state *const fpstate = __this_cpu_read(fpsimd_last_state);
+ struct task_struct *tsk;
+
+ if (!fpstate)
+ return;
+
+ tsk = container_of(fpstate, struct task_struct, thread.fpsimd_state);
+ if (test_tsk_thread_flag(tsk, TIF_SVE))
+ fpsimd_flush_cpu_state();
+}
+#endif /* CONFIG_ARM64_SVE */
+
#ifdef CONFIG_KERNEL_MODE_NEON
DEFINE_PER_CPU(bool, kernel_neon_busy);
@@ -286,11 +1111,13 @@ void kernel_neon_begin(void)
__this_cpu_write(kernel_neon_busy, true);
/* Save unsaved task fpsimd state, if any: */
- if (current->mm && !test_and_set_thread_flag(TIF_FOREIGN_FPSTATE))
- fpsimd_save_state(&current->thread.fpsimd_state);
+ if (current->mm) {
+ task_fpsimd_save();
+ set_thread_flag(TIF_FOREIGN_FPSTATE);
+ }
/* Invalidate any task state remaining in the fpsimd regs: */
- __this_cpu_write(fpsimd_last_state, NULL);
+ fpsimd_flush_cpu_state();
preempt_disable();
@@ -325,6 +1152,7 @@ EXPORT_SYMBOL(kernel_neon_end);
static DEFINE_PER_CPU(struct fpsimd_state, efi_fpsimd_state);
static DEFINE_PER_CPU(bool, efi_fpsimd_state_used);
+static DEFINE_PER_CPU(bool, efi_sve_state_used);
/*
* EFI runtime services support functions
@@ -350,10 +1178,24 @@ void __efi_fpsimd_begin(void)
WARN_ON(preemptible());
- if (may_use_simd())
+ if (may_use_simd()) {
kernel_neon_begin();
- else {
- fpsimd_save_state(this_cpu_ptr(&efi_fpsimd_state));
+ } else {
+ /*
+ * If !efi_sve_state, SVE can't be in use yet and doesn't need
+ * preserving:
+ */
+ if (system_supports_sve() && likely(efi_sve_state)) {
+ char *sve_state = this_cpu_ptr(efi_sve_state);
+
+ __this_cpu_write(efi_sve_state_used, true);
+
+ sve_save_state(sve_state + sve_ffr_offset(sve_max_vl),
+ &this_cpu_ptr(&efi_fpsimd_state)->fpsr);
+ } else {
+ fpsimd_save_state(this_cpu_ptr(&efi_fpsimd_state));
+ }
+
__this_cpu_write(efi_fpsimd_state_used, true);
}
}
@@ -366,10 +1208,22 @@ void __efi_fpsimd_end(void)
if (!system_supports_fpsimd())
return;
- if (__this_cpu_xchg(efi_fpsimd_state_used, false))
- fpsimd_load_state(this_cpu_ptr(&efi_fpsimd_state));
- else
+ if (!__this_cpu_xchg(efi_fpsimd_state_used, false)) {
kernel_neon_end();
+ } else {
+ if (system_supports_sve() &&
+ likely(__this_cpu_read(efi_sve_state_used))) {
+ char const *sve_state = this_cpu_ptr(efi_sve_state);
+
+ sve_load_state(sve_state + sve_ffr_offset(sve_max_vl),
+ &this_cpu_ptr(&efi_fpsimd_state)->fpsr,
+ sve_vq_from_vl(sve_get_vl()) - 1);
+
+ __this_cpu_write(efi_sve_state_used, false);
+ } else {
+ fpsimd_load_state(this_cpu_ptr(&efi_fpsimd_state));
+ }
+ }
}
#endif /* CONFIG_EFI */
@@ -382,9 +1236,9 @@ static int fpsimd_cpu_pm_notifier(struct notifier_block *self,
{
switch (cmd) {
case CPU_PM_ENTER:
- if (current->mm && !test_thread_flag(TIF_FOREIGN_FPSTATE))
- fpsimd_save_state(&current->thread.fpsimd_state);
- this_cpu_write(fpsimd_last_state, NULL);
+ if (current->mm)
+ task_fpsimd_save();
+ fpsimd_flush_cpu_state();
break;
case CPU_PM_EXIT:
if (current->mm)
@@ -442,6 +1296,6 @@ static int __init fpsimd_init(void)
if (!(elf_hwcap & HWCAP_ASIMD))
pr_notice("Advanced SIMD is not implemented\n");
- return 0;
+ return sve_sysctl_init();
}
core_initcall(fpsimd_init);